Radiation polymerizable acrylate- and methylacrylate-functional polysiloxanes have been described in U.S. Pat. No. 4,306,050 to Koepner. The patentee describes a process in which organopolysiloxanes having chlorine atoms attached to silicon atoms are reacted with pentaerythritol triacrylate or pentaerythritol trimethacrylate. The compositions prepared by this process, however, have the acrylate group linked to the silicon atom by a carbon-oxygen bond, thereby rendering the compositions hydrolytically unstable.
U.S. Pat. No. 3,878,263 to Martin describes acrylate functional polysiloxanes wherein the acrylate functional group is bonded to the silicon atom by means of a hydrolytically stable carbon-silicon bond. However, these acrylate functional polysiloxanes cure slowly when radiated with actinic radiation.
U.S. Pat. No. 4,201,808 to Cully describes acrylate functional polysiloxanes wherein the degree of acrylation is increased by having the acrylate groups linked to a silicon atoms by means of carbon-silicon linkages as well as silicon-oxygen-carbon linkages, thereby enhancing the reactivity of the composition when irradiated with actinic radiation. However, these compositions are hydrolytically unstable.
U.S. Pat. Nos. 4,606,933 and 4,762,887 to Griswold et al describe acrylate-functional polysiloxanes in which the acrylate containing group is bonded to a silicon atom by a carbon-nitrogen bond. However, it is difficult to prevent chain extension in these compositions, often resulting in a yield of highly viscous materials.